In the prior art, a motor driving apparatus in a device such as an electric vehicle mainly includes a series-connected battery group 101 and a three-phase inverter 102, as shown in FIG. 1.
However, different initial capacities, internal resistances, self-discharge rates, and the like of storage batteries in the series-connected battery group 101 lead to a difference between charge/discharge characteristics of the storage batteries, and the difference further widens after the storage batteries are charged and discharged for a plurality of times, resulting in a decrease in a storage battery capacity and output power, and a relatively low storage battery utilization.